[ppt]engineering graphics- basics - · web view1. try to write a description of this object....
TRANSCRIPT
1. Try to write a description of this object.
2. Test your written description by having someone attempt to make a sketch from your description.
Effectiveness of Graphics Language
The word languages are inadequate for describing the size, shape and features completely as well as concisely.
You can easily understand that … *1
Freehand drawing The lines are sketched without using instruments other than pencils and erasers.
Example
Drawing by use of InstrumentsInstruments are used to draw straight lines, circles, and curves concisely and accurately. Thus, the drawings are usually made to scale.
Example
Drawing by use of ComputerThe drawings are usually made by commercial software
such as AutoCAD, solid works etc.
Example
Elements of Engineering Drawing
Engineering drawing are made up of graphics language
and word language.
Graphicslanguage
Describe a shape(mainly).
Wordlanguage
Describe size, location andspecification of the object.
Basic Knowledge for Drafting
Graphicslanguage
Wordlanguage
Linetypes
Geometricconstruction Lettering
Projectionmethod
Standards are set of rules that govern how
technical
drawings are represented.
Drawing standards are used so that drawings convey
the same meaning to everyone who reads them.
DEFINITION
ISO International Standards Organization
Standard Code
ANSI American National Standard InstituteUSA
JIS Japanese Industrial StandardJapan
BS British StandardUK
AS Australian StandardAustralia
Deutsches Institut für NormungDINGermany
Country Code Full name
Drawing Sheet
Trimmed paper ofa size A0 ~ A4.
Standard sheet size (JIS)
A4 210 x 297A3 297 x 420A2 420 x 594A1 594 x 841A0 841 x 1189
A4
A3
A2
A1
A0(Dimensions are in millimeters)
Drawing Scales
Designation of a scale consists of the word “SCALE”
followed by the indication of its ratio, as follow
SCALE 1:1 for full size scales
SCALE X:1 for enlargement scales
SCALE 1:X for reduction scales
• Definition: • Scale is define as ratio of linear dimensions of an element of
an object represented in the original drawing to the linear dimension of the same element of the object by itself.
Visible lines : represent features that can be seen in the
current view
Meaning of Lines
Hidden lines : represent features that can not be seen in the current view
Center line : represents symmetry, path of motion, centers of circles, axis of symmetrical parts
Dimension and Extension lines indicate the sizes and location of features on a drawing
Lettering StandardANSI Standard This course
Use a Gothic text style,either inclined or vertical.
Use all capital letters.
Use 3 mm for mosttext height.
Space between linesof text is at least 1/3of text height.
Use only a vertical Gothictext style.
Use both capital andlower-case letters.
Same. For letters in title block it is recommend to use 5~8 mm text height
N/A.Follows ANSI rule.
GOOD
Not uniform in style.
Not uniform in height.
Not uniformly vertical or inclined.
Not uniform in thickness of stroke.
Area between letters not uniform.
Area between words not uniform.
Example : Good and Poor Lettering
Leave the space between words equal to the spacerequires for writing a letter “O”.
Example
Sentence Composition
ALL DIMENSIONS ARE INMILLIMETERS
O O OO UNLESS
OTHERWISE SPECIFIED.O
References- IMAGE 1. http://www.bibliocad.com/library/piston_638102. http://www.dreamstime.com/royalty-free-stock-photo-engine
ering-drawing-equipment-image193356153. http://trade.indiamart.com/details.mp?offer=47154093134. http://en.wikipedia.org/wiki/Set_square5. http://nptel.ac.in/courses/112103019/36. http://grafoindia.com/drawinginstruments.html
• http://www.engineering108.com/pages/Engineering_graphics/Engineering_graphics_tutorials_free_download.html
References- Contents
• http://www.engineering108.com/pages/Engineering_graphics/Engineering_graphics_tutorials_free_download.html
• A text book of engineering graphics- Prof. P.J SHAH
• Engineering Drawing-N.D.Bhatt• Engineering Drawing-P.S.Gill